The [[physical memory]] of computers can be imaged and analyzed using a variety of tools. Because the procedure for accessing physical memory varies between [[operating systems]], these tools are listed by operating system. Once memory has been imaged, it is subjected to [[memory analysis]] to ascertain the state of the system, extract artifacts, and so on.

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I hereby license all my contributions to this wiki (before and after

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One of the most vexing problems for memory imaging is verifying that the image has been created correctly. That is, verifying that it reflects the actual contents of memory at the time of its creation. Because the contents of memory are constantly changing on a running system, the process can be repeated but the results will never--to a high degree of probability--be the same. Thus, repeating the acquisition and comparing the results is not a feasible means of validating correct image creation. [[Memory analysis]] can reveal whether the image's contents are consistent with the known layout and structure of a given operating system, as well as answering other questions, but it cannot answer the question as to whether the image accurately reflects the system from which it was taken at the time it was taken.

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March 19th, 2006) under the [http://creativecommons.org/licenses/by-

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sa/2.5/ Creative Commons Attribution-ShareAlike 2.5] license.

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== Memory Imaging Techniques ==

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; Crash Dumps

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: When configured to create a full memory dump, [[Windows]] operating systems will automatically save an image of physical memory when a bugcheck (aka blue screen or kernel panic) occurs. [[Andreas Schuster]] has a [http://computer.forensikblog.de/en/2005/10/acquisition_2_crashdump.html blog post] describing this technique.

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; LiveKd Dumps

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: The [[Sysinternals]] tool [http://www.microsoft.com/technet/sysinternals/SystemInformation/LiveKd.mspx LiveKd] can be used to create an image of physical memory on a live machine in crash dump format. Once livekd is started, use the command ".dump -f [output file]"

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; Hibernation Files

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: [[Windows]] 98, 2000, XP, 2003, and Vista support a feature called [[hibernation]] that saves the machine's state to the disk when the computer is powered off. When the machine is turned on again, the state is restored and the user can return to the exact point where they left off. The machine's state, including a compressed image of [[physical memory]], is written to the disk on the system drive, usually C:, as [[hiberfil.sys]]. This file can be parsed and decompressed to obtain the memory image. Once [[hiberfil.sys]] has been obtained, [http://sandman.msuiche.net/ Sandman] can be used to convert it to a dd image.

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: [[Mac OS X]] very kindly creates a file called '''/var/vm/sleepimage''' on any laptop that is suspended. This file is NOT erased when the machine starts up. It is unencrypted even if the user turns on [[File Vault]] and enables Secure Virtual Memory. [http://pc-eye.blogspot.com/2008/08/live-memory-dump-on-mac-laptops.html].

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; Firewire

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: It is possible for [[Firewire]] or IEEE1394 devices to directly access the memory of a computer. Using this capability has been suggested as a method for acquiring memory images for forensic analysis. Unfortunately, the method is not safe enough to be widely used yet. There are some published papers and tools, listed below, but they are not yet forensically sound. These tools do not work with all Firewire controllers and on other can cause system crashes. The technology holds promise for future development, in general should be avoided for now.

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: At [[CanSec West 05]], [[Michael Becher]], [[Maximillian Dornseif]], and [[Christian N. Klein]] discussed an [[exploit]] which uses [[DMA]] to read arbitrary memory locations of a [[firewire]]-enabled system. The [http://md.hudora.de/presentations/firewire/2005-firewire-cansecwest.pdf paper] lists more details. The exploit is run on an [http://ipodlinux.org/Main_Page iPod running Linux]. This can be used to grab screen contents.

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: This technique has been turned into a tool that you can download from: http://www.storm.net.nz/projects/16

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: Goldfish is a tool that is being developed to get RAM from a Mac. Contact cybercrime.com.

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== Memory Imaging Tools ==

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===[[Windows]] Hardware===

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; Tribble PCI Card (research project)

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: http://www.digital-evidence.org/papers/tribble-preprint.pdf

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; CoPilot by Komoku

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: Komoku was acquired by Microsoft and the card was not made publicly available.

: On [[Microsoft Windows]] systems, [[dd]] can be used by an Administrator user to image memory using the ''\Device\Physicalmemory'' object. Userland access to this object is denied starting in Windows 2003 Service Pack 1 and Windows Vista.

:[[Fastdump]] (free with registration) Can acquire physical memory on Windows 2000 through Windows XP 32 bit but not Windows 2003 or Vista. A version of the program able to work on Windows Server 2003 and above called [[Fastdump Pro]] is rumored but is not currently available.

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===Unix===

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;[[dd]]

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: On Unix systems, the program [[dd]] can be used to capture the contents of [[physical memory]] using a device file (e.g. <tt>/dev/mem</tt> and <tt>/dev/kmem</tt>). In recent Linux kernels, /dev/kmem is no longer available. In even more recent kernels, /dev/mem has additional restrictions. And in the most recent, /dev/mem is no longer available by default, either. The throughout the 2.6 kernel series has been to reduce direct access to memory via pseudo-device files. See, for example, the message accompanying this patch: http://lwn.net/Articles/267427/.

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;[http://www.pikewerks.com/sl/ Second Look]

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: This memory analysis product has the ability to acquire memory from Linux systems, either locally or from a remote target via DMA.